The present invention relates to a new and improved method of, and apparatus for, producing a uniform textile fiber sliver or the like which is taken-off from a sliver supply device, for instance a carding machine, and taken-up by a driven take-up or receiver device.
The equipment of the present invention is of the type wherein the fiber sliver removed from the sliver supply device is guided through a regulation drafting arrangement possessing a pair of measuring rolls and a driven pair of drafting rolls, one measuring roll of the measuring roll pair being driven by the sliver supply device and the other measuring roll being deflected as a function of a change in thickness in the fiber sliver traveling through the measuring rolls. Further, the drive speed of the pair of drafting rolls and the take-up device are regulated as a function of a deflection of said other measuring roll, and the drive speed of the take-up device is additionally regulated as a function of the length of the fiber sliver between the pair of drafting rolls and the take-up device.
Such type equipment has been disclosed for instance in Swiss Pat. No. 505,221. With this apparatus difficulties nonetheless can arise. Changes in the speed of the carding machine are only here incompletely compensated, because only a possible effect upon the thickness of the fiber sliver after detection by means of deflection of the one measuring roll produces a corresponding change in the drive speed of the pair of drafting rolls and the take-up device. At higher operating speeds, such regulation operates much too sluggishly. A further difficulty resides in the fact that with the heretofore known apparatus there is provided between the pair of drafting rolls and the take-up device only a fiber band-intermediate storage having an indicator for indicating the degree of filling. In this case, there are formed numerous superimposed loops of the fiber sliver. Only after complete emptying or overfilling of the fiber sliver-intermediate storage are there delivered appropriate control commands to the drive devices. At high operating speeds a fiber sliver-intermediate storage, which receives a multiplicity of superimposed fiber sliver loops, oftentimes is the cause of disturbances.
Further, there is known a similar type of apparatus from U.S. Pat. No. 3,862,473 wherein equally there is provided a regulation device for the drive speed. However, here the sliver supply device, a first pair of rolls and the take-up device are rigidly drivingly interconnected with one another. A separate drive is only provided for the pair of drafting rolls. The regulation device likewise is controlled as a function of the thickness of the fiber sliver. Owing to the common control of all drive elements, which are rigidly interconnected in driving relationship with one another, there is however only possible a special control with respect to the drafting rolls, not however also an independent control of the not even present different drives for accommodation of the individual elements to one another. High operating speeds are then only possible if there are tolerated frequent disturbances. The known apparatus furthermore possesses a fiber sliver-intermediate storage which, if desired, produces by means of two light barriers an additional influencing of the regulation device. The one light barrier merely determines that fiber sliver has been deposited into the fiber sliver-intermediate storage. The other light barrier responds when the fiber sliver-intermediate storage is empty and the remaining fiber sliver loop, during its increasing shortening in length, has been pulled past the light barrier. This only then occurs if a large tension is present in the fiber sliver. Under normal operating conditions there should not arise any response of the second light barrier.